本文要点：
共价有机框架是技术应用中下一代薄膜的有吸引力的候选者。然而，由于它们的结晶性质、在普通溶剂中的不溶性以及在高温下的不熔化性，使得自发生长它们或将它们加工成薄膜具有挑战性。
在此，作者报道了一种基于调节剂-溶剂诱导聚合过程制备共价有机框架膜的有效策略。
在共价有机框架生长的初始阶段，调节剂的加入减缓了成核速率，导致易于加工的流体前体的形成。随后，引入合适的干燥过程以平衡溶剂的蒸发速率和诱导的调节剂的结晶速率，导致形成具有无定形和结晶结构的混合物的共价有机框架膜。
这种策略对于制备多种类型的具有大规模独立状态的共价有机框架膜是通用的。此外，具有不对称结构的共价有机框架膜可以用作有机蒸汽触发的致动器，提供优异的可重复性和可逆性。
通过在成核过程中引入荧光、手性和催化剂等功能分子，可以很容易地制备功能多样的共价有机骨架膜，从而赋予其更广阔的应用前景。
Fig. 1 | Strategy illustration and applications of functional COF-LZU1 films
Fig. 2 | Characterizations of COF-LZU1 films. a SEM image ofthe surface of COF-LZU1 films (insertis the digital image ofCOF-LZU1 films). b Cross-sectional SEM images of COF-LZU1 films. c AFM image of the surface of the COF-LZU1 films. d XRD spectrum of the surface of COF-LZU1 films.
Fig. 3 | Formation process of COF-LZU1 films. a Binding energy between reacted molecules. b Selection of modulators. SEM images of synthesizing COF-LZU1 films with (i) citric acid and (ii) p-toluenesulfonic acid. c SEM images of COF-LZU1 film in (i) closed condition and (ii) open condition. Insert is the digital image of COF-LZU1 film in the (i) closed condition and (ii) open condition. d FTIR spectra of COF-LZU1 films at different reaction time. e XRD patterns of COF-LZU1 films at different time. f Schematic representation of the COF films formation mechanism.
Fig. 4 | Extension of COF films
Fig. 5 | Vapor stimuli-responsive actuators. a Bending-recovering behavior of COF-LZU1 films (5 mm × 1 mm) placed in an ethyl acetate vapor or air atmosphere at room temperature. b Images of a flower with a closed-open-closed transformation upon alternate exposure to ethyl acetate vapor or air. c Plot of the reversible deformation cycles of the COF-LZU1 films. d Schematic illustration of the bendingunbending actuation of a COF-LZU1 films.
Fig. 6 | Encapsulation of functional molecules. a Schematic diagram of the encapsulation of functional molecules in COF films. b XRD spectra of functional films. c Fluorescence spectra of BP@COF-LZU1 film under 350 nm excitation. d CD spectroscopy of L(+)-TA@COF-LZU1 film. e SEM-mapping of Grubbs-II@COF-LZU1 film.
https://doi.org/10.1038/s41467-024-55114-z
